Method of die casting



INVENTOR? fiur/vn E Hal/WW flfiprfiwf A Hemds/ ATTORNEY '7 Sheets-Sheet l B F HCLMES ET AL METHOD OF DIE CASTING Nov. 28,

Filed Dec.

NW. 28, 1950 B. F. HOLMES EI'AL 2,532,256

METHOD OF DIE CASTING Filed Dec. 10, 1947 '7 Sheets-Sheet 2 INVEN TURF Burfon ff/o/me's d: Her/5W1" hf #6/7108/ A 7' TMNEY Nov. 28, 1950 B. F. HOLMES ETAL ,532,256

METHOD OF DIE CASTING Fil'ed Dec. 10, 1947 7 Sheets-Sheet 4 /N VENT 0R5 Eurfan fHa/mas & M rtar) hf He/hde/ Nov 28, 1950 Bf'F. HOLMES ET AL METHOD OF DIE CASTING Filed Dec.

'7 Sheets-Sheet 5 B. F. HOLMES ET AL METHOD OF 'DIE CASTING Nov. 28, 1950 7 Sheets-Sheet 7 Filed Dec. 10, 1947 d mm a w 23 w w Wm mg mam my INVENTOR. r/an ff/ofnmui Haber/H Hwnae/ bav Alb

A TTOPNE Y KR -36 Jam Patented Nov. 28, 1950 UNI; D 15 PATENT OFFICE i METHOU OF DIE CASTING -Burton F.-Holme"s-and Herbert H. Heindel, To-

ledo, Ohio, assignors to Schultz Die"Casting Company, Toledo, Ohio, a corporation of Ohio Application December 10, 1947, Serial No.790,838

1 This: invention *IBlBJtESybO an electrically :operated, automatic control fOI'rdi-Ef casting machines, including an extremely accurately: controllable, Electra-mechanical :means -for 1 increasing I the productivity of :a -die casting machine. The-new method involvesthe efficiency-of the die casting operations and particularly armoreaccurate control of the injectionof the'metaL-in twostagesin- Acludingr its retention in .the' die under pressure ttorrcorr ect solidification and correct and improved methocl'of cutting oil the supply.

.1Funther-bbjectsaand advantages are within the scope of this invlentionysuch 'aSw relate to the :details of ithelop'eration of thermethodas will be .under'stoodiromarconsidera'tion of the specifica v tion. andl'drawin'gsrof certain forms "of the inven- I tion, onetoffllwhichfmay be preferred, in which:

.Figure I is a diagrammatic viewof one ,ty'peof die casting machine: to which 1 0111" invention has -been=applled-+Figure I representing the operation of closingthe'di es.

Figure IIsisailiagrammatic view similar to Fig- "ure I; inswhichia preliminary or delayed injection of the casting mettal operation-is takingplace.

Figure: IIIrisaai: similarrdiagrammatic illustraitio'n of the: machinerdnring the "maininjection operation;

' A 1 separate Figurei IV? :is mot included although an important separate stepi is hereinafter described. Themechanism in step IV is the same as that illustratedinFigure III;

Figure 4V is a similan diagrammatic illustration showing thetcooling time of themachinelwith the air control" piston returning to normal I position;

u'Eigure VI,;is-a diagrammatic illustration of-a mechanism illustrating the; opening of I the dies Figure VII- is any, electrical, diagram of a, con- .trol embodying :ourinvention as applied to the type of meohanism illustrated in Figures I through VI;

Figure VIII -is-a. view similar to Figure VII .of

l'a-modification ot the circuits and respective controls thereof.

In certain embodiments of our invention, we have shown-a: certain: electrical control. system, -which we have invented as applied -to the operation otthe clie castmgmachine;suchas thatillusl trated :in: the-tpriorcpatents to .Schultz et all for Method "for Casting Metals, Patent No. i2,l08;08();'dated February 15, 1938, and ;to Schultz .et :al. for Apparatus for Casting Metals, Patent xiNo; 2173, 377; dated-September, 19,1 1939.

a Fundamentally,your invention relates to a n electronic; control system or (method. for controltiling-lithe valves of themechanismwhich operates of Figure I, theaction of the machine and the operation of our electrical control involves the following sub-steps:

A. Operator presses closebutton 23, Wirihgdi- :agram Figure VII (23, FigureVIII).

B. Tube 5 fires--relay it and coil of oil pilot valve is energized in FigureVII. In Figure VIII, relays 402 and 496 energize coils Ii and valve 30'. C. Main oil valvefiSa on die casting machine is thereupon operated-so that oil piston fillanioves rack 59a, rotating gear 54a, pitman rod l'lmmoving die plate a in direction of arrowto close the dies A and B.

nrMachine thus closes.

E. Machine locksup and closes microswitch 2'! GFigureVII) In Figure VIII, the machine moves switch ($82 to closed position. In both casesuthis .eiIects timesdelay firing-1 of tube l controlled in Figure VIIby potentiometer it and in Figure VIII by potentiometer 66 i.

In Figure II, the following steps are involved:

A. Tube llfires.

Air .pilot valve coil 5! is energized through rela-y'ii'. A. sourceof air pressure supply:-is obtained from a suitable compressor system for all air valvefand air. piston operations.

\ C. This causes operation of supplementary air cylinder and piston i332 acting: to turnt-he shot 'leverfltc, causing operation of main air valve84a,

"which exhausts air from below main air operthe top of rpiston-Ma.

,D. This starts main air cylinder pistonr-3 2a slowly downwardly at reduced pressure in delayed shot action.

E. Tube 2 has not yet fired but is on its delay period set by potentiometer ii, as shown in Figure VII, or potentiometer 65! as shown in Figure VIII.

In Figure III the following steps are involved:

A. Tube 2 fires.

B. Air pilot valve coil 6! is now energized through relay l2.

C. Regulating or check valve mechanism [42a is opened wide by air pressure supplied from air pilot valve 6 i a for coil l.

D. Main air cylinder now receives full air pressure behind piston 32a and main metal injection takes place with a heavy shot, the full pressure on the metal being in excess of one thousand pounds per square inch as indicated in the prior Schultz patents above referred to, in contradistinction to prior art types of machines in which the metal is open to atmospheric pressures.

E. Tube 3 has not yet fired but is on its time delay which is controlled by its potentiometer 42 as shown in Figure VII or potentiometer 5M as shown in Figure VIII.

Step IV, illustrated in Figure III, involves the following sub steps:

The mechanism is in the same position as in Figure III including the position and operation of the valves, as indicated at the end of cycle of Figure III, hence, no special diagram is illustrated of this Step IV. Step No. IV is mainly for permitting the metal in the die to become (set' A. Set time operation which begins with the end of shot operation and is the time between the firing of tube 2 and the start of main air cylinder pistons return caused by the firing of tube 3 (which has not yet fired), in the embodiment illustrated in Figure VII.

In the embodiment of Figure VIII, the start of the main air cylinder pistons return is caused by the firing of tube 3.

B. Pressure is held on the metal during the time delay for the firing of tube 3 which is determined by the setting of its potentiometer 42. as shown in Figure VII or potentiometer 66! as shown in Figure VIII.

In Figure V the following sub steps are involved:

A. Tube 3 fires rebiasing tubes l and 2 and starting the time delay for tube 4.

B. Air pilot valve coils 5i and 6! return to their de-energized positions.

C. Air is applied to top of piston 332 for operating lever 83a to return main air cylinder valve 84a to its initial position to supply air to the bottom of piston 32a.

D. Air is cut off from pilot line of air controlled valve mechanisms actuated by air pilot valve coils 8!, which is now de-energized, allowing spring 382 to reset it.

E. Main air cylinder piston 32a begins its return stroke regulated by the bleeder 35! valve setting on return check valve 322.

F. Cool time is the delay setting of the potentiometer 33 for tube :3, as shown in Figure VII or potentiometer 55! as shown in Figure VIII.

Figure VI involves the following sub steps:

A. Tube 4 fires.

B. Machine control holding circuit opens circuit including relay 25B is opened by relay 39,

illustrated in Figure VII, while in the embodiment illustrated in Figure VIII, relay A22 is opened by relay M2.

C. As shown in Figure VII, tube 5 is rebiased, deenergizing oil pilot valve coil 36 which causes machine to open. Since oil valve 63a is now returned to the position shown in Figure VI, and oil is supplied to the top side of the piston 6%, moving rack 53a, downwardly, turning gear 54a in the direction of the arrow so that pitman arm 41a now opens the dies A and B, as shown in Figure VI. As illustrated in Figure VIII, tube 5 is omitted entirely and the firing of tube 4 acts through relays M2, tea and 4% to deenergize oil pilot valve coil 36 which permits dies to open as described for Figure VII.

D. Machine opening causes microswitch 21', illustrated in Figure VII, and 662 (Figure VIII) on safety bar 93a to open.

E. As shown in Figure VII, this energizes relay 33 causing bias to be reapplied to tubes 1, 2, and 3, stopping flow of plate current in tube 3 which de-energizes relay iii. As shown in Figure VIII, opening of microswitch 582 provides bias to all tubes, the tubes and 2 having been previously rebiased by the firing of tube 3.

F. In both embodiments (Figures VII and VIII) the rebiasing of tube 2 resets the circuits for the next cycle of machine operation.

The main control of the die casting operation is by one hydraulic mechanism (for die operation) and two air controlled valves operated through the network disclosed including the main relays H], H and i2 so that the proper operations of these relays controls the machine operation step by step as indicated.

It is important that the safety button 22 is normally closed, and when it is closed the Z l-volt current is supplied to the main manual quick return control button 23-43 in Figure VIII. This main control button 23 is a momentarily operated type, which, when pressed by the operator, supplies current to the relay 2U, energizing the relay, thereby closing points 2| which are thereupon held closed continuing thereafter to maintain the machine in automatic control for one complete cycle. The machine then automatically stops so that the operator may remove the casting. All parts of the machine are then in proper position for recycling the operation and the operator may continue producing castings at will.

Embodiment illustrated in Figure VII The first operationclosing the dies (Figure I) is effected by firing of the thyratron of space discharge tube 5. The tube 5 is, until firing, under a normal bias of '75 volts. When the relay 20 is energized, it also operates point 24 which short circuits the bias circuit to the grid of tube 5 through the condenser 25 and resistance 25. This action of removing the bias from tube 5 causes the same to fire (through the time delay mentioned), and this operates relay It, its corresponding contacts and supplies 440 volts to the main oil pilot valve 3!! for closing the die casting machine.

When machine closes, microswitch 21A, which is normally open, also closes thereby applying 24 volts to relay coil 33. Relay 33 has three relay points normally closed which apply bias to tubes I, 2, and 3. When coil 33 is energized, these three points of relay 33 open, and the bias is removed seriatim from each tube l, 2, and 3, and each condenser 35, 36, and 31 for each such tubes I, 2, and 3 will discharge through their corresponding potentiometers 40, 4|, and 42, according to the setting of the potentiometers.

This triple ioontact relay 33,--*while= operating the points, simultaneously has the effect of causing the tubes I," 2, and 3 to fl-rein series, due -to the varioussettings of their respective potentiometers 40, 4|, and 42.

Specifically, :tube I I fiPESwWhBIl "its grid voltage reaches the critical apoint. Current thenfl iiows from tube Ithroughlead; 49, resistorbdll', to relay coil I2 energizing the sameandclosingits normally open contactonor switch: 52, thereby applying-440 volts to shot air valve' 5l. -When air valve-51 :operates in the die casting machinait operates a two-way air cylinder, rwhich-rturns the shot lever, turning the main tour-way air valve. This is! thefirst-part of therinjectingcthe .metal (which is done throu'gha oheck valve :controlled by tube 12, hereinafter ldescribedhand theair is completely removed from thetlower *side of the main air cylinder.

Tube 2 operates ina similar manner to supply moves its checking eifecton themain operation:

.oi wthe casting r-machine, and nowothe main Step ofinjectingithe metal quickly is accomplished by themachine.

In View of the fractithatbothtubes I and 2have :nowfired, a pressure is held on the "metal in the I die for a certain. length of *time, whichis very important in this die casting machine. This pressure of the dies closed is .1 held until: tube 3 fires,

which removes this as willalnow be. described.

Thyratron tube- 3=is interconnected in the systemtthrough relay III] so that when tube 3 firesgit again changes the lcontrolgridsof tubes I and 2 back tobiasposition. Tube 3 has its time delay (through condenser? .31, potentiometer 42, hereinafter described), and'this action-holds the pressure on the dies, as just stated. Firing of tube 3 has the effect of releasingboth coils 5I-and 6 land their .correspondingiair valves, and the machine parts are mechanically returned to normal.

Thus, upon firing of tube 3 (when relay fiii hasurs .acted as stated above) a current flows through the coil of relay .contactor 1 I] and :closes the two nor- .mally open switches II and 12cand-opens=the one normally closed switch I3. The two closed switches nowoperate to-reapply bias to tubes I and 2 which breaks the plate circuit=-and-deenergizes relays II and I2 and thus removes -the 440 volts from the two air Valves 5i and IiI. Actually, in'the die casting machine at this point, the air valve 5| has the double function of now causing the lever to -.be turned back to normal position, which allows the main air valve to turn back to normal position allowing the piston to return to normal, sincerair is admitted to the other side. In the meantime, releasing air valve 6 I has released the check valve previously: referred to as controlled by tube 2.

= Current input circuit to 110 and 220, respectively. The -lead I'DZ fOlHJhB.

to the other'side of the transformer I01. :circuit, however, is merely a momentary circuit, and it requires the operation of a hold circuit being connected to ground lead I33.

variations in supplyvoltage. meets to lead 18.5, which is the main bias supply .33 and point 72 ofrelay Hi.

220 volt circuit extends fromthef secondary III I to the point of time delay relay I03,.the pointbeing designated by the numeral I04. 'This pointfiis normallyopen. Upon energizing relay I03, this point closes and connects lead 102 through lead 'safetyopen switch22rto :theipoint 2 I .of'the relay ZUdescribedabove. When the automaticswitch 23 is "closed, this energizes the relay 20; as indicated supra. For the purpose of energizing coil .20, a lead H5 Iisconnectedwith lead H3 and through automatic closed button 23, lead I-IZI,

through lead II8, to the relay 20 as shown. The

return circuit startsqfrom relay 20 through lead H9 and is connected to lead I20, which returns This to actually control the relay 20 which will be hereinafter described.

For controlling relay 1 0, the control voltage is applied to the 24 volt .coil .20. When 'the button r23. ispushed, voltage is applied across rtheaelay 2.0,energizing the relay and causing the biasto be shorted out on tube 5, as indicated above, which causes the tube to :fire after a short time delay due to the condenser 25 and resistor26. This operates the relay 'Ill and its switch, which supplies 440 Volts to the main oil pilot valve coil causing the machine to "close.

The microswitch 21 is normallyopen, butjis closed when the machine locks up-'which.is

done mechanically as in the prior patents above referred to:-and closing microswitch 21 thereby applies voltage 24 volts to relay 33.

Transformer IIll supplies 6.3 volts from secondary I'Il to the filaments of each thyratron tube I, 2, 3, 4, and 5 (circuit not shown) Another secondary I12 oftransforrner Hi! supplies 5'volts to the filament of rectifier tube I13. Another secondary I'M supplies voltages toplates of rectifiertube I73 throughleads H5 and I16, as shown. A center tap I'FI is connected. to a filter condenser I86, the other side of said filter This center tap I1 is also connected to resistor I 8I connecting lead I 82 to relay coil I03. The other-side of coil IE3 is connected by lead I83 to regulator tube I85 cathode, the anode being connected to ground lead I33.

Bias supply for tubes 1, 2, 3, 4, and 5 Tube I85 maintains '75svolts across it despite Lead 283 also conlead for'all the 'thyratrontubes I, 2, 3, i, and 5. Specifically, this" is; arranged by providing a set 'ofiilters for each tube, excepting tube 5.

i For tube I, We have shown connected from lead 186; a :filter, consisting .of a resistor I90, condenser I9I, connected .to ground lead I33 and between the two at point I92, there is a lead I94. This lead I94 is connected with point I95-on relay The other side of point. 955 is connected by lead I86 to the control rid of'tube 1. Lead I95 is also connected to the normally open point I2 of relay it). This contro grid :is the trigger actionfortube I.

The filaments of each of tubes I to 5 is supplied Wit1l6.3V01tS circuit from the secondary Ill of the bias transformer Iii].

, In .operationzof tube I; thepoin't 155. 01; relay 33 being; normally vclosedgrher biasasupplynthrough 7 lead I83, resistor I90, from point I92, lead I94, point I95, lead I55, charges the condenser 35. When the bias is removed, as will hereinafter be further referred to, the point I95 opens by reason of the action of relay 33, and consequently, the condenser 35 will then discharge through the potentiometer 43 and a controlling resistance 1233 to the ground lead I33. This resistance 235 is to limit the flow of current when the potentiometer is set at zero, which would otherwise draw too much current from the bias supply at I92 and might ruin the potentiometer 45.

The bias for tube 2 is identically arranged as described in connection with tube 5, the corresponding resistor and condenser having the con :nection 25A for lead 252, which is connected to point II of rela I5, point I! having lead 253 for connection to the control grid of tube 2, the tim ing circuit for tube 2 being by way of condenser 36 and potentiometer 4 I. We also provide a limiting resistance, such as 235 for tube 2.

The bias for tube 3 is from connection 255, through lead 255, to normally closed point 25'! of relay 33, lead 233, to the control grid of tube 3. Tube 3 also has a timing circuit similar to that described, supra, as to tubes I and 2, by way of condenser 3i and potentiometer 52.

The bias for tube 4 is from connector 2H lead 2 to normally closed point l3 of relay 75, lead 2I2 to the control grid of tube El which also has .a timing circuit similar to that of tubes I, 2, and 3, but by way of condenser 55 and potentiometer 43. The firing of tube 3 will be hereafter set forth.

The bias for tube is from the main bias lead I86 through current limiting resistor 2I5, lead 2I5, lead 2i? to normally open point 25 of relay 20, lead 2I6 also being connected through time dela resistor 28 to the control grid of tube 5.

The firing of tube 5 and removal of the bias occurs when normally open point 24' closes by reason of the action of relay 25. When point 25 closes, the lead 2 I! becomes a ground connection, since point 24 is now connected through lead 225 to ground lead I33.

When relay 25 operates to close point then the condenser 25 for tube 5, which is holding the voltage on the grid of tube 5 due to the charge of condenser 25, discharges through resistance 25, lead 2I3, 2I'I, point 24, lead 225, to ground I33.

The operation of firing of tube 3 which has the eflect of opening the casting machine will now be described.

To do this, since tube 3 has fired, the bias supply has been removed from tube 4 (after the time delay, through potentiometer 2-3 and condneser 45 has taken place). This energizes relay coil 55 through connector I35, which has 220 volts A. 0. being connected to point I54 of relay I53. The other side of relay 85 has lead I3i, resistor I32 to the plate of tube 4. The cathode, which is the return circuit of tube 5, is connected by lead 33 to ground I34.

Rela 35, having now been energized, it opens normally closed point 3E which is in the holding circuit for relay 25 coil. This removes current from relay 20, allowing it to deenergize and open point 2| and point 22, which restores bias to tube 5 and hence deenergizes oil pilot valve 30 which operates fluid to main oil valve and mechanical means such as spring X eifects an opening of the dies, as will be understood.

As a safety device, we also have a control, so that if any air is on the main air cylinder (which 8 injects the metal) the dies cannot open. To do this, we have an air pressure operated switch I40 connected from point 2| by lead I4I to one side of I40. The other side of switch I45 is connected by lead I52 to lead II8 to relay 23. This puts switch I40 across relay point 8| and prevents the holding circuit from being opened or broken as long as there is air pressure in the upper side of the main air cylinder.

We also have a further control so that with certain dies necessitating the cores being removed before the die is opened, the machine will not open but shows a light so that the operator may time his operation and actually remove the core before the machine is opened. To do this, we use a double pole manual switch I50 which maintains, when closed, voltage on relay 20 even though relay would have otherwise opened 20 as when tube 4 fires. To this end, we provide a set of points I5I for switch I50. Lead II8' connects to I5I through lead I52, and the other side of switch I55 is connected by lead I53 to lead I4I to point 2I of relay 20 (hence to supply circuit).

The pilot light circuit (controlled by switch I50) is as follows: 110 volts from supply circuit lead IE5 is connected to point 82 of relay 80, lead ISI to pilot light I52, lead I53 to switch I50. The other side or point I55 of switch I55 connects with lead 554 to ground lead I33.

We also provide a manual circuit whereby the machine may be manually operated in conjunction with the foregoing, and in this connection we provide a manual automatic switch 225 connected. with input lead 95 having a lead 226. In the drawing, the switch 225 is shown in the automatic connection with the point 22'! closed to transformer I53. When it is desired to use the machine manually, the switch is closed to the point 228 which'is normally open and also the pilot light circuit. The lead also connects through lead 233, resistance 23 I to the pilot light 233, resistance 234, return lead 235, connection 235, lead 23! to the other input supply lead SI.

The coil 22? has a lead 240 connected with normally closed push button switch 24I lead 242 and switch 245. The other side of the switch 245, which is open, is connected by lead 246 to the return lead 235. By closing switch 245 manually, the coil 221 is energized because a closed circuit has been established to the input and output main lines and 9|. When this is accomplished, point 228 closes and applies 440 volts across the oil pilot valve 30 for the main casting machine connection. When the relay 22'! is energized, it also closes the point 251 and establishes a holding circuit for coil 221, by reason of connection 242 to lead 243, to point 24? which is now closed, and lead 242 connects the same to return lead 235 which brings it to lead 9|.

When point 228 of the relay 221 closes, a lead 255 connects the same with coil 30 of the oil pilot valve, it being understood that the main input circuit from lead 23 connects through lead 225 to the point 228 as well as the coil 221.

We also provide circuit arrangements for connecting the power line to the motor of the machine, which builds up the oil pressure for operating the machine. Moreover, these circuits control the connections for the main input supply lines 90 and SI. To this end, we provide a push station 265 interconnected with the three leads 25!, 262, and 253. These three leads are push station leads from a magnetic starter (not shown) which connects the main outside power lines to the leads 95, 9I and 92.

waste.

Emb d en ustr t dl i ure V II We show in Figure VIII, a further embodiment;

of our invention, Here, the diagrammatic connection from the power line to the machine is indicated at 23 whichincludes the automatic return push button tdil which, being connected to,

of Figure VIII. Lead 4Ei5extends; frcmswitch; liihlead c635 torelay 405 having normally open switch point 626 on the power panel and connected with the input circuit as will be. hereinafter pointed out. Then, a 1ead 4il? extending from the other sideof relay switch point 525 connects with relay Ill causing an operation of the pilot valve and hence the die actuating mechanism. The other side of this circuit from coil, ill is by lead 4 i d, point 625 of relay 405,, hence, by lead its to main power switch relay 438 i (the input circuits to be described This 24. volt circuit closed by relay ill energizes coil ill) to close the dieoperating mechanism, the circuit for coil 35 being a 440 volt circuit from the power line.

Tubes fire insequence, efiecting casting machine operation Following the operation of said die closing circuit controlled by relay 402 in Figure VIII, the thyraton tubes l, 2, 3, and 4 fire as in Figure VII. Tubes l and 2 control themetal injection in two stages. Tubes 3 and 4 reset tubes I and 2. Thus, tube I fires causing slow injection of molding metal as shown in Figure II; then tube. 2 firesreleasing the long valve of check valvemechanism Him to permit a full shot of metal as in Figure III; tube 3 first holds the time delay after tubes I and 2 have fired,and then-when tube fires, it resets tubes I and. 2 (releasing their valves) when tube 4 fires, it unlocks die closing mechanism allowing dies to cpenall as will hereinafter more fully appear.

Power input circuit-Figure VII-I The 3 phase inlet leads 90, 91, 92 are for a standard type of 3 phase motor 95', the motor which produces the oil pressure for the die operating mechanism and includes a branch lead 441 (from input lead 90) to a standard type of contactor shown bracketed at 442. Another lead connects 9| with contactor 442. A standard type of push button mechanism 443 is used to ener: gize contactor 442, thereby applying power to motor 95 and also supplying 440 A. C. volts to relays III, II and E2 to coils3li, 5| and 6|.

A safety feature is here provided, in that if contactor 442 for any reason opens it removes the power from the main injection operating air valves 5! and 6| and oil valve 30', thus preventing squirting metal into the room. To do this, we provide power leads 445 and 446 in these coil circuits, lead 446 passing through the points of contactor 442 as shown. Thus, if contactor 442 is opened, then novoltage will beapplied to coils 30, 5!, 61, because the operating circuits to said coils will be opened.

Transformer circuit (from input-leads 90 a d 91) Figure VIII Connected with input leads 90 and-.91 iweqfirst provide fuses 45iland145l and leads 452landc453 tothe switch points. of another contactor having,

coil 456'having transformer 45'! and outlet, points 45 8,and 455, This energizes transformer 45'! and a 'seconda'ryvoltage (24 volts) from transformer 4511s appliedtocoil 456 through switch 454 by leads459 and 465: Then, by leads 46! and 462 voltage is appliedto a main tapped transformer 465; which has a440 volt: primary and a 220 voltage secondarytappedat volts to give another or. third reduced circuit voltage of 110 volts. A circuitground lead 46.! is grounded at 468.

Tubesupply circuits-Figure VIII We provide a-22 0 volt circuit from transformer 45,5"?(saidcircriit to be hereinafter further described) for "the purpose of supplying current to the -pla'tes"of thyratron tubes L 2, 3, and 4, and also fthrough an additional transformer to the 24 voltage control circuit.

We also provide -a 110 voltage circuit from transformer 455 (said circuits to be hereinafter further described) to supply another transformer for lighting-the filaments of tubes i, 2, 3, and 4 at 6.3 volts and another circuit for a heat control "instrument hereinafter also 1 described,- this also includes 5 volts for a rectifier tube and :a high voltage forthe plate of the same to supply D. C. current to-the grid bias circuits for the main thyratr-on tubes I, 2, 3, and 4.

The 110 volt=circuit from-main transformer 465 includesfuse 46 9 lead 410 to normally open point 4T i,=1ead4l2 toconnecting point-4'13, which supplies through lead 545 the 110 volt primary of transformer 475. The 110 volt circuit from main transformer -465 also has lead 416 connectedto lead 478 from said transformer said lead 416 extending to terminal 41-!- tosupply 110 volts for gas; supply and heat control.

Details tube supply circuitsFigure VIII Referring-how ,to .the above mentioned 220 volt circuitjfrom transformer-465,, the same includes fuse 486;; lead} 48f tonprimary of transformer 482 TR2 The; other: side, of the primary of said transformer 482;; isgroundedatlllifl from lead 483.

The 24 volt control circuit This transformer 482 has a 24 volt secondary winding with lead-484 .to-a terminal point 486 and by lead 487 through coil 406, the other side of 0011486 having lead, lead 488;to terminal 490, hence to switch 49! (normally open) to terminal 492,, lead 49.5., and lead 485 to other side of transfarmer 482. Thus, when switch 49! in this circuitis closed coil 406 is energized and this closes switches to effectan application of voltage to the system forautomatic operation of the machine; 'Ifhereforaswitch 49! is a key switch by means ofwhich the mechanism may be disconnected-from-all automatic operation and, in certain instances; the machine may be operated manually.

This- 24 i volt control circuit also connects through lead 48-4,- =lead 494; to both points 455 and lfiii of relay 436.

Relay 430- is provided-to give a delaying action to applicationof220 volts to'the platesof tubes t, 2, 3," and 4 "and to the control circuit (above described.) for-relays 462. and M2, to allow tubes ll 430. The other side of coil 439 is connected by lead 485 to transformer 482.

The plate circuits for the tubes includes the terminal 468 as a common grounded cathode circuit from transformer 465. On the other side from said transformer, the plate circuit includes the fuse 496, lead 558, to normally open point 50I on relay 465 when point is closed in the automatic position of the apparatus. From point 50I we provide lead 552 to normally open point 583 on relay 435 also closed in the automatic position after time delay for the tube warm up has taken place (hereinafter described). Lead 505 from point 553 connects with terminal 506, all tube plate circuits connect from terminal wire 506. Thus, for tube I, we have a lead 551 connected to lead 555, resistor 596 to limit the current flow, lead 599, to coil I5, lead 5 to the plate of tube I. The cathode circuit of tube I is grounded as indicated by a circuit 5I3. We also have a condenser connected across coil 5l9 to supply current to coil on the negative /2 cycle and prevent chattering.

The other tubes 2, 3, and 4 are similarly connected.

Thus, for tube 2, lead 5I4 is connected to the lead 566 common to all of tubes I, 2, 3, and 4, as indicated supra. Lead 5I4 connects through resistor 5I5, lead 5E6, to coil 596, hence by a lead to the plate of tube 2 as shown. A condenser 5I9 is connected across leads 5I5 and 511, as

shown.

For connecting tube 3, we provide a lead 520 passing through the resistor 52 I to lead 522, which connects with coil 655 having lead 524 connected to the plate of tube 3. A condenser 525 is connected across leads 522 and 524. The cathode circuit of tube 3 is grounded as indicated by circuit 526.

For tube 4, we also provide a lead 538 connected with a common connecting lead 566, limiting resistor 53I, lead 532, coil 4E2, lead I3I, to the plate of tube 4. We also provide a condenser 535 across leads 532 and l3I as in the case of the other three tubes. The cathode of tube 4 is also grounded by circuit 531, as indicated.

Bias circuits The bias circuit for each of tubes I, 2, 3, and 4 will now be described.

110 volts from the main transformer 465 through relay 495 connects by lead 412, point or terminal 413, which is connected by lead 545 to the primary of the transformer 415 and returns by 546 to ground as shown at 541.

The transformer 415 has three secondaries, one 556 for the 6.3 volts for the filaments of the tubes I, 2, 3, and 4. (Tubes are thyratron.)

Another secondary output circuit of 5 volts is indicated 55l for the rectifier tube 553.

The third center tapped winding 554 is for supply voltage to two circuits, one the plates of a rectifier tube 553 and the other for the main thyratron tube bias circuits. We have grounded the filament (cathode) of rectifier tube 553, as shown. At the center tap of secondary 554, we have a lead 555 to resistor 556, lead 551 combined choke and relay coil 499. From lead 551 we also have a lead 558 to condenser 559, the other side of which is grounded as shown.

From coil 499 we have lead 566 to the cathode of voltage regulator tube 56l, the plate of which is grounded as indicated. Across tube 56I is a resistor 562 connected by lead 563 to lead 560 to 12 said tube 56!, the other side of resistor 562 being grounded.

Our connections for these tubes also forms a time delay for the warming up of tubes I, 2, 3, and 4, since relay 499 has a time delay on the make of points 499 with a well known type of switch which has quick break.

Moreover, this relay 499 provides a safety arrangement since failure of any part of the bias supply will cause 499 to open, dropping out relay 430 which disconnects the plate circuits of the tubes I, 2, 3, and 4. This also drops out the 24 volt control circuit to the automatic operation.

Connections for the bias supply voltage and tubes 1, 2, 3, and 4 The above circuits and the tube 553 and 56I provide means to produce the bias voltage for the main thyratron tubes I, 2, 3, and 4. We will now describe its connection to these tubes. Thus, we have a main bias supply lead 565 joined to lead 553 as shown, which lead 565 connects with three points (normally closed) on relay 566, points 561, 568, and 569. Lead 565 is also being connected with the points of relay 600, namely points 519, SH, 512, and 513. This lead 565 also has a connection to lead 515 to a contact 516 of relay 5I8. Lead 565 is in the main bias supply line for all four tubes.

For tube I, bias is normally supplied from lead 565 to point 561, lead 511, resistor 518, the lead 519, to the grid of tube I.

For tube 2, the bias is from point 568, lead 530, resistor 58I, lead 582, to the grid of tube 2. For tube 3, the bias includes lead 583 from point 569, to resistor 584, lead 585, to the grid of tube 3.

For tube 4, the bias includes a lead 581 from point 513 to resistor 588, lead 589, to the grid of tube 4.

Sequential firing of tubes We have provided means for causing tubes I, 2, 3, and 4 to fire in sequence one after the other, and moreover, any subsequent tube in the series cannot fire until the preceding tube has fired. The circuits and means for accomplishing this will now be described. Thus, when relay coil 566 is energized, this opens points 561 and 568 and 569 removing bias from tube I. The bias for tube 2 is now supplied only through an auxiliary circuit including a connecting lead 515 extending from lead 565 to switch point 516, lead 598, lead 580, resistor 53I, lead 582 to grid of tube 2. When tube I fires (at the end of its time delay, to be described) relay 5"), through lead 5i I, is then energized and normally closed point 516 now opens, removing the bias from tube 2.

Also, the firing of tube i and energizing of coil 5H], closes the normally open point 592 thereby applying 24 volts to the power relay I2 by leads 631 to valve 5I to operate the metal injection at reduced pressure as will be pointed out.

Firing of tube 2 At the expiration of the time delay for tube 2 tube 2 fires (bias being removed by tube I, as stated supra). This action opens normally closed point 595 of relay 596 which removes bias from tube 3, energizing coil 596 and also closes normally open point 591 which, through lead 598, energizes relay II for operating the check valve mechanism 6| to give the full shot, as will be pointed out.

amazes 13- Firz'ng of tube 3 Removing bias from tube 3 allows tube3 to fire at end ,of its time delay energizing the coil of relay 600, closing normally open; points 510 and 51!, reapplying bias to tubes I and 2, thus resetting thesetubes and their associated plate.

circuit relays;

Firing of tube 4 Moreover, normally closed points 512andp'513 are openedand since 5121s opened, this prevents reapplying bias to tube 3 by tube 2 at this point of the cycle. The opening of 513 removes bias from tube 4.

Whentube 4 fires at the end of its time delay, the relay 412 is energized, opening normally closed point 413 which breaks the holding circuit for the die operating mechanism, above described. This holding circuit being removed, coil 30 is deenergized, and this permits the dies to open by a spring return of the die actuating control,.mechanism.

Time delay circuits fortubes 1, 2, 3 ancM Referringto tube], we have a circuit which includes lead511 (bias supply lead for tube resistor 518) lead 519 to grid of tube I. When normally closed, point 561 opens, there is a circuit through resistor 518,- lead 519, which also charges condenser 650..which bias is removed, suppliesavoltage to grid I until it is discharged through adjustable potentiometer 66l and current limiting resistor662 to ground L3 as shown. The otherside of the biascircuit and tube cathode is grounded as described supra. Thus, the setting of the adjustment on potentiometer 661 determinesthetime .fordischarge of condenser 660 which, when it reaches critical grid voltage of tube I, allows the tube to fire. Resistor 662, limits the current. for. a very lows-or offsetting of the potentiometer 66L. Resistor 51.8 has two it purposes, one to prevent main bias supply from being shorted in case condenser 660 fails, Also it provides a bufferaction to prevent burning of point 561, due tosudden inrush of current to condenser660 It will be understood u that we have provided similar potentiometer time control discharge networks for each-ofthe other tubes 2, 3 and 4 and in the drawings we have used the same numerals as for tube- I.

Reapplyin-g bias to tube 3 The bias control of the tube 3 (and also I and 2) is interlocked with the microswitch 602 which switch, in turn, is actuated by the rack on the machine, whichrack is operated by thehydraulic system for the, die operating mechanism; The microswitch also has point 603 (normally closed).

Closing of point 602 by said rack or machine operated part closes relay 665. This is accomplished by circuits connected, with power, input relay 430 which includes lead 408;, from contact 496 of relay 430,;and leads,40 9 and 606. Another lead 601 alsoconnects from 606 toa point 608 (normally open) of relay 412.;

On the other side of coil-605', a lead 6l0-connects with normallyopenvside of, microswitch 602, referred to supra ,anclleaclfiil, leads 652, 424 and 425, normally openpoint 426 on relay 430.

When coil 605 is energized, coilof relay 566 is also energized. Relay 605 has three normally open points, 61 2', point 6l3- and 61 4 The connection from relay 605 to relay 566 includes point 612-, lead 6 l-5,-relay coil 566. From the other side (if-relay 566; lead 616 connects to lead Bypoint 14: 4 P0 of relay 402;- the-oth'er side-of the switch; 4146 has U a *lead 4l 1 extending; to terminal- 4 I 6 lead 4H3 has a lead4 l1- extending to terminal 4 l6, lead 6 it through safety point 6| 0 =of 640 open button (normally closed) which also connects to lead- 620 and connection 62!; lead 623,- which cons t 11.0, ad 06 c m let n the circuit, or n: ergizing. coil 60,5.and hence coil 566. Energizing coil 566 opens all three points 561, 568, and'569, which removes bias from tuber I and; allows it to beremoved in sequencefromtubesrZ and 3,, and the bias to tube-3 is reappliedrby. point; 569 :of res lay 566 when relay 566- is.deenergizedas the .ma-. chinempens by breaking thelmicroswitch at point 602-. In themeantime, bias ontubes l. andi2 has been restored when tube 0 3 fires, as stated-supra,

Pressure switch, control. for, preventing machine from. opening when metal ,is beincinjected; into dies 0 We provide a special safety controlwinrconnece tion with preventing. metal injection; .whengthe diesare open and also an, improper actionincase, the. operator accidentally presses control; part Thus, from .relay 406 (towhich currentis. supplied from transformer 482-);- weprovida a, circuit from point 625 of relay 406 to a, pressure: switch 628:;by. leads,.405,r408,x651;, 652,- 424;lpoint, 6|:3J0f relay 605, lead .629, to pressure. switch620q This pressure switch. 628 is located (across the die open and. closingcontrol circuit in such a wayastto prevent the .machine opening, butcannot .ac-. cidentally close it. When the machineis in automatic control position, relay. 430,,is: energized thereby closing points 496:and points 426, as stated supra, and 24 volts is supplied through point 496, lead 406, 409 to normally open point 625 on relay 406 and in theautomatic position, this point 625 is? closed,.allowing voltage then presentat point 625 to passthrough lead 4l0.,to coil of relay l0 to coil 30.- The otherside of,-relay l0by; lead 401- connects with, anormally open point 626(c1osed in automatic position), lead 629 to point 6l3 ofrelay 605.v From relay 605 thebther side of 613 connectsby lead 424 to re-. turn control voltage lead 425, point...426,. of, relay 4:0. supplying. energy at 24 volts fromtransformer 4 2.

Safety circuit for preventing pressure switch from closing the machine-Pressure switch merely holds machine closed while metal is being iny'ected Point-6B onrelay.605, is primarily for connects ing pressure switch 628,. which is an. electrical contact on a pneumatically operated mechanical pressure switch in such a manner that; the pressure switch, while: it may hold thelmachine closed as long as, air pressure exists on switch,628.,-yet if air pressure is supplied accidentally, such action willnotresult in theclosing of machine from an open position since relay 605 .mustqbe energized tohold point 6 l 3. closed before the pressure switch canbe effective to supply energy to the coil l0 (die closing), if switchpoint 613 is open, such connection will be broken. The microswitch point 602 controls relay 605, and the machine mustbe closed before 605 is energized. Hence, if the machine is not closed; 605 isdeenergized and point H3 is open so that no energycan be suppliedto coil 10.

Pilot light circuit When pressure switch 628 is closed; we provide a signal light-630110 show that the-pressure switch.

is operating. Thus, we connected to the 24 volt control circuit by point 496 of relay 430, lead 408, lead Bill, to lamp 630 and from lamp 030 by lead 632 to pressure switch 628, through pressure switch lead 629, point N3 of relay 605 and returning through lead 424 to point 426 of relay 430.

Circuit to prevent relays 11 and 12 from contacting until dies are closed When microswitch 002 is closed, this energizes relay 605, and hence closes points 612 and (H3 and GM as indicated supra. When point 6I4 closes, we have a safety circuit from point 6l4 which is connected on one side to lead 424 to 24 volt pilot circuit. From relay 605 at the other side of point 6M, we provide a lead 635 which connects to relay coils II and i2 in series. Referring to coil II, we have a lead 598 connected to point 591 of relay 596, through said point 591, leads 409, 408 to the other side of the 24 volt circuit at point 496 of relay 430.

This safety circuit just described, also controls relay I2. Thus, from lead 635 (for relay H) We also have a lead 636 to relay l2, and from relay I2 by lead 631 we connect to point 592 of relay Microswitch must be in correct position We have a further circuit to correct a condition, when in operation microswitch 603 becomes jammed in position requiring an injection of metal into the die. This additional circuit acts as a safety circuit to prevent such an improper injection of metal in case operator presses close button. When operator presses close button point 640 of the switching connections indicated at 23' to start automatic cycle voltage control, through point 819, safety button point 8%, lead 64L through safety point 523 of the microswitch, lead 608 to coil 4532, which completes the closing circuit for coil 482, this closes the machine. However it will be seen that if point 693 is in metal injecting position, the operator will not be able to close the machine, since point 583 would be open if the microswitch is not in its normal position for the start of the cycle.

Safety circuit to prevent machine operation by accidental closing of microswitch We also have a normally closed point 603 of the microswitch connected in such a manner as to prevent operator from closing the machine if the microswitch is jammed. If point 682 of microswitch is closed accidentally, unless at correct normal position, relay 492 has not been energized leaving point 4H3 normally open. Relay 568 and associated points 56? and 563 are actually the controlling points for the two stage metal injection through coils H and I2. Thus, if microswitch is accidentally closed, causing relay 605 to close, starting shot cycle, relay coil 566 will not be energized even if point EH2 of relay E305 has closed, because the other side of coil 556 has its circuit broken, by normally open point 418 which will not be closed unless machine is in normally operating cycle by action of the automatic close button 640. The manually controlled automatic station and the microswitch control circuits are therefore dependent upon each other as indicated.

Emergency switch for stopping automatic action and causing machine to open and mechanism to be reset In the automatic operation of one complete cycle of the machine, the relay 4512 acts as an electric self locking in means for effecting the supply of current to the various circuits heretofore described. As will be seen from Figure VIII and the foregoing description, this current supply is a 24 volt circuit which includes lead 820 on one side and 424 on the other. We also provide, however, an emergency switch in the form of a momentary contact Bis which is normally closed, but which may be opened to break this locking in circuit. Referring to the drawings, this is accomplished as follows:

The 2% volt circuit referred to flows from lead 628 through the normally closed, momentary breaking, safety button 689, through lead BIB, point ilt, lead 4, to relay 482. This relay 402 is energized when the machine is operating in which case point N3 of this relay 432 will be closed. Thus, current from lead E2tl-4|'t passes through point 418, lead M0, to point M3 of relay 4l2, through this point, through leads M5 and 40%, to the coil of 462, through the coil of 222, back to lead #124, which is the other side of the 24 volt supply. Since the locking in 24 volt circuit for relay 392 is supplied between the leads 42d and 62d, and this emergency safety button 8l9 is interposed between these two leads, it will be seen that when the operator opens the switch SIS, the locking relay 402 is released and the shot cycle resets and the dies of the machine open.

Pilot light for heat control instrument We also have a heat control pilot light 645 in a circuit to the 24 volt transformer 482 con nected on one side through leads 484, 480, 491, lead 645, light 645. From the other side of light 645, we have a lead 64'! to leads 492, 493 and lead 485 to the other side of transformer 482. Thus, when the heat control on and off switch 454 is closed (which is a toggle switch) it energizes relay 456 through leads 459 and 450 applying 440 volts to transformer 465 (primary) to supply H0 (secondary) for the heat control motor and gas valve (not shown). Also, this energizes transformer 482 from the 220 secondary of transformer 465, which supplies 2e volts to the pilot light 645 through the circuit, just described supra. When switch 454 is closed, it applies 24 volts to the pilot lamp 645 showing the operator that the heat control and gas valve section of the cabinet is on. Relay 4% has a transformer 451', the control circuit of which is 24 volts supplied by said transformer from the 440 volt circuit. This avoids the necessity of supplying 440 volts at any time to the control section of the cabinet.

Pilot lamp for indicating machine ready for antomatic action We also provide a lamp 650 connected by lead 65| to lead 408, hence to point 496 of relay 430. On the other side, lamp 850 is connected by lead 052 to lead 425 to point 426 of relay 430. Operator closes switch 49l, thereby energizing relay 406 throwing the circuits into automatic p0S1 tion. This energizes bias transformer 415 and connected circuit, which at the end of its time Manual control circuit We have a manual automatic switch 49! operable when relay 406 is not energized. The control by switch 49[ is dependent on switch 665. Thus, if manual switch 665 is closed, 24volt control voltage from transformer 482 will flow through lead 485, lead point 656 of relay 43!), lead 66'! to the manual open and close switch 685, lead 568, point 659 (closed) through the lead 491 to the coil of relay l forthe die operating mechanism. Thereturn circuit is through lead 4H3, point 610 (closed) lead til, to point 495 (relay 430), lead 494, lead 484, to other side of control. transformer 482. Thus, when the mechanism is in manual position, determined by the position of switch 49l, and. switch. 665 is closed, 24 volts is applied across the coil of relay Ill, operating pilot valve 34 to open and close diesof machine but the rest of machine, includn metal injection, will not operate.

Resume of circuits-Figure VIII From the foregoing, it will be seen that we provide the following main circuits and controls:

.(l) POXVER INPUT CIRCUIT Through leads 9!], BI, and 92, we supply three phase alternating current, 440 volt current, to the power panel of our combination power panel and electrical control mechanism.

(2) TRANSFORMER AND, VARIOUS TRANSFORMER CIRCUITS We provide a preliminary transformer 45'! and connecting circuits therefor; the main transformer 465 for providing circuits for 220 volt and 110 volt; 24 volt control circuit transformer 482; and the bias circuit transformer 415 all with inter-related circuits, as herein appears.

(3) MACHINE OPERATING CIRCUITS From the foregoing, it will also be seen that we provide a 440 volt circuit for the main ma chine operating electrical means including the motor 95' for producing oil pressure to operate the die closing mechanism, the coil 30 for operating the electric control for die closing, and the coils 5| and SI for the two stage metal injection operating means.

(4) CONTROL CIRCUITS We provide several interrelated and interconnected control circuits to properly effect the application of the foregoing machine operating circuits just referred to. These control circuits are supplied with current at 24 volts and primarily are for operating the coils HI, H, and 12 to in turn eifect an operation of the die closing mechanism and the two stage metal injection referred to; These control circuits are basically controlled by the thyratron tubes l and 2 (tubes 3 and 4 being for resetting). We also providea ascents to theoil pressure motor through contactor 442 through push button stage 443. Each of these circuits includes the various relays as hereinbefore set forth, a complete operation following this list of circuits. The supply of control voltage to coil I0 isprimarily through relay 4E2 when the automatic system has been put into operation through the close button manually operated switch 640. For energizing coil5 l by means of control coil [2, we provide relay 5E3 connected in the plate circuit of tube 1 for effectingthis result. For operating coil ti through control coil ll, relay 593 in the plate circuit of tube 2 produces this action.

(5) SAFETY CIRCUITS We provide two solely safety circuits in the switch point6133 of the microswitch, if the latter is not in the correct position, as indicated supra, under the sub-title, Microswitch Must Be in Correct Position. We also provide another solely safety circuit in the connection through the switch point GM of relay 605 to prevent the operation of the metal injection in case the dies are not closed, as describedsupra under the subtitle, Circuit to Prevent Relays II and i2 From Contacting Until Dies Are Closed.

(6) PILOT LAMP CIRCUITS From the foregoingdescription, it is als clear that we provide pilot lamp indicators to advise the operator of the machine the various conditions as referred to in. describing said pilot lamps.

Operation-One complete cycle As the dies are closed, the microswitch is operated by a part of the die closing mechanism to thereby throw the microswitch to close 602 position andeffect an energization of relay 695. The machine is held by a mechanical action of a toggle mechanism disclosedin the Schultz et a1. Patent No. 2,173,377; referred to supra. Relay 64 5 closes switch point i312 andrelay 565 is energized, opening point 561 whichis in the bias circuit for tube l, as described supra. the tube 5 bias, permits tube l to fire at the end of its time delay through its plate circuit, thereby energizing relay 5Hl, closing switch point 592, as stated supra. This, through the various circuits, above described, energizes relay I2, which, in'turn, supplies power to the pilot valve for the main air cylinder 5!, permitting a delayed shot of metal at reducedpressure to be injected. into the die as the first part of the two-stage metal injection at the reduced pressure on the metal as above indicated. Specificallygclosing of switch point 592 by the discharge of tube l connects leads 4&8 to point 496 of relay 430, point 496 being normally closed; hence to lead 434 of the:

Opening 19 lead 631, and as clearly shown in the drawing, to relay 2. The other side of this relay circuit includes lead 635, 535, to point GM of relay 605 (now closed through 6M, lead 424, 425 to switch 426, lead 485 to transformer 482).

The firing of tube l energizes coil and causes the action illustrated in diagram of Figure II of the drawings, in which the dies, having previously been closed, solenoid air valve 5| permits movement of the piston 332 and the correlated parts, illustrated in the diagram of Figure II, as described supra, permits a slow injection of metal by a slow movement of piston 320, at a relatively low pressure of the metal and all air beneath the piston 32a is removed by the adjustment of valve 84a, as described supra. This is an important feature of our invention since we have found that by removing all of the air beneath the piston 32o, when the next cycle of operations takes place, it permits a very strong satisfactor injection of main metal into the dies avoiding complicated arrangements heretofore regarded as necessary.

Temporary auxiliary circuit for biasing tubes 2 and 3 It will be noted from the wiring diagram of Figure VIII that we also provide in addition to the main biasing circuit above described an auxiliary bias circuit for tubes 2 and 3. To this end it will be noted that we provide a lead 515 from main 'bias supply lead 565, lead 515 connected through normally closed point 516 of relay 510 and lead 595 to the bias circuit 580, etc., for tube 2. This auxiliar circuit for tube 3 we provide in an additional lead 512' extending from point 512 of relay 6B9, hence by lead 595' to lead 583 which connects to the bias circuit of tube 3. This auxiliary biasing circuit for tubes 2 and 3 is on temporarily simultaneously with the main bias supply described above.

Firing of tube 2 It will be noted as indicated above, when relay 566 has been energized the main supply bias at switch points 568 and 569 have also been broken at the same time when the bias supply was broken to tube l. However, the auxiliary bias supply circuits for tubes 2 and 3 still prevents tubes 2 and 3 from firing.

By the firing of tube I, just described, this auxiliary bias for tube 2 is also opened because switch point 516 which is in the bias circuit for tube 2, has now been opened by rela 510. Removing tube 2 bias causes the discharge of its circuit at the end of its time delay, and energizes relay 596. Thus, when point 591 is closed, current is supplied from the transformer 482 to relay circuits and switches, since We have provided a lead from the lead 458, numbered 409, to switch point 551 (lead 488 being connected to transformer 482 as just described) and from switch 591', lead 598 to relay II. On the other side of relay H, we have a lead which joins lead 635 just described. Hence, the connections are established back to the transformer 482, as just described in connection with tube I. As will be understood from the foregoing, the energization of relay H in turn connects the 440 volt power line to the coil 5| of the air pilot valve which causes the main injection of metal at high pressure into the closed die since it effects opening of large valve of the valve mechanism 142a consequently producing the high pressure on the 20 molten metal, all as illustrated in. Figure III of the drawings.

Holding the pressure of the metal in the dies, known as set time An important feature in our invention is the correlation of the electric controls herein described, which at this point in the cycle of operations, permits the apparatus to remain in the position it is in when the step illustrated in Figure III is completed and the piston 32a. has reached the bottom of its stroke carrying with it the metal injection piston, illustrated diagrammaticall thereunder. The apparatus is now held in this position with the pressure on for a desired length of time called set time. The time delay in the bias circuit through the potentiometer 6H of tube 3 prevents its discharging until the metal has set in the die as described supra.

After set time, firing of tube 3 Next in the cycle of operations, we provide means through the firing of tube 3 to reset the bias circuits for tubes l and 2. This is done by establishing a temporary additional biasing circuit hereinafter described. The resetting of the bias of tubes l and 2 is done primarily by first removing the above described auxiliary bias from tube 3 by opening the switch point 595 f relay 595 which, as stated supra, occurs when tube 2 fires. Removing the bias from tube 3 therefore causes a discharge after the time delay shown, as will be understood, through its plate circuit. Firing of tube 5 energizes relay Eeu which is in the plate circuit of tube 3, as shown so that energization thereof closes switch point 510 and 5H, which are in an additional temporary bias circuit which, as shown in the drawings, includes main suppl line 555 which is connected through the now closed switch points 516 and Eli, point 51H connected to the bias of tube I through 510' and 511 while the temporary additional bias for tube 2 is connected through point 51!, lead 51!, lead 5% connecting to the bias of tube 2. By closing these switch points 510 and 51!, tubes 1 and 2 are rebiased through these additional circuits just described. It is understood that when the proper bias is applied to tubes 5 and 2 discharge tliereof through the plate circuit ceases.

Prevention of rebiasing of tube 3 To prevent rebiasing of tube 3, we have also provided another switch point 512 for relay 609 so that when relay 65b is energized, as just stated, this switch point 552 opens with the result that reestabllshing bias through the additional circuits just described to tubes l and 2 will not also re-establish through the auxiliary circuits bias to tube 3.

From the foregoing, it will be understood that when bias is re-established to tubes i and 2, these tubes cease firing and coils H and I2 are deenergized, permitting solenoid operated pilot valves 5| and SI to be returned to normal position. After tube 3 has fired, the apparatus is in the position illustrated diagrammatically in Figure V in which the pressure has been removed from the metal in the dies and a period of time, called the cooling time, is allowed for the metal to cool, which is the time preceding the firing of tubes in our electrical circuits the cooling time being controlled by potentiometer 661 o tube-4.

Firinao'f tube 4 opens the dies machine and.

circuits thereby reset to initialpositz'on Firing of tube 6 accomplishes the re-opening of the dies. Referring back to tube 3, it will be noted that when it fires, it has opened switch point 573 on relay 68!] which, in turn, removes the bias from tube 5 after its time delay through its potentiometer circuit 6| i, tube 4. When the bias on tube 4 is removed, then the tube discharges, energizing coil 512, opening point M3 on Automatic rebiasing' of each of the tubes after mechanically completing one cycle of machine operation When Jrellay 562 is de-energized, as stated supra, effected by the firing of tube 4, then relays 605 and 556 are also both de-energized, This closes the switch points 561, 568 and 569 so that now bias is resupplied to both tubes 3 and 6 as well as to tubes l and 2. This is due to the fact that the bias supply line 555 as indicated supra is connected with points 561, 568 and 569 controlled by relay 566 and under normal inoperative osition of the machine the closing of these tube I, the lead 585 for the bias circuit to tube 2, the lead 583 for the bias circuit to tube 3. It will be also noted that the main bias supply lead line 565 is connected with relay point 573 of relay 60!] and since this point is now closed, lead 58? supplies the bias to tube 4. P c-int 513 is closed because of the fact that tube 3 has now been rebiased and therefore relay 665 has been deenergized and spring means closes the contact 513. Rebiasing tube 3 in this manner thereupon permits its relay coil 656 to effect opening of points 5?! and 576, thereby disconnecting the additional bias circuit which was temporarily established for tubes I and 2. The entire electrical apparatus is now in initial position. The machine then will not recycle until the operator restarts the cycle by pressing manual close button 665, as described supra.

Interconnection control for supply of bias and It will be noted that we have an important interconnection in the circuit arrangements so that before the machine can be operated, there is a warm up time i or the several thyratron tubes and also an interconnection, so that if the bias should fail, due to abnormal conditions, such failure opens the main plate circuits of the several tubes so that they would not discharge, as otherwise this would cause an improper operation of the die casting machine. Circuit 556 is for the heaters of the thyratron tubes,

The transformer 115 provides a 5 volt circuit 551 for the filament of the rectifier tube 553. Also the bias circuit for the several thyratron tubes I, 2, 3, and 4 is supplied from transformer 415 (changed to D. C. by rectifier tube 553) the bias circuit including center tap winding r554, lead a connected to the plates of rectifier tube 553, the

filaments thereof also groundedas shown. (The cathode circuits for each or the thyratron tubes are likewise grounded.) Resistor 556 also has a connection-through main lead 55'? to the coil 469 which, being in the bias circuit, as stated above in the description, and shown in the drawings, is alsoarranged toact as a combined choke and relay, the point 599' being of the type which is slow making and quick breaking. Connected to the coil 295 by lead 565, which connects by lead 563 to the main bias supply line 565 for the main thyratron tubes, we also provide affirther regulating means in the regulating tube 56l which is grounded as shown. Moreover, across (the tube 56 i, a resistor 562 is further employed to control the circuits, resistor 562 being grounded as shown.

The switch 495' of coil 499 is as shown in the control circuit for the plate voltage of the several thyratron tubes, so that upon energizing relay 495, the slow closing of the plate circuit through switch point 459' gives the tubes a chance to warm up in their internalcircuits before the plate voltage supply is connected to said tubes. Moreover, as stated supra, if there is any failure in any of the bias supply circuits for the tubes, since the same passes through relay coil 499; and this must be energized to close switch 499' in the plate circuits of the tubes, failure of the bias circuit :xio en the rela oint 499', ndhenc d o t points closes the bias circuit through lead 57? to p s y p a e nnec s the plate supply circuits to tubes 1, 2, 3, and 4.

Manual control for operating opening and closing of dies and circuits In order to permit the operator to open and close the dies, at will, without the rest of the machine operating, as may be necessary, we provide an independent circuit manually controlled, which operates merely the coil ill for operating the die closing mechanism.

Thus, we provide a manually controlled switch 665, which is a circuit extending from the transformer 482 to energize coil I0 independently of the automatic controls described above, said circuit being established to the power input or disconnected therefrom according to the position of the manual-automatic changeover switch 49!. For one side of manual switch 665, we provide a lead 668 and a lead 661, which extends to points 665 on relay 436 closed with the manual-automatic changeover switch 49! in the manual position. From switch point 666 of relay 436, lead 485 connects to the 24 volt circuit from the transformer 482. Then by lead 484, lead 494, switch point 495, lead 6', switch point 610 of relay 406, normally closed under these conditions to'lead M6 to coil [0. From the other side of coil l 0, lead 40! connects to switch point 6'65 and from lead 668 to the other side of the main manual switch 665 just referred to.

In order to accomplish the foregoing, as indicated, we provide the relay 466 to isolate the rest of the machine so that this manual control may be operated. In order to accomplish this isolation, we provide the relay 466, whose energization is controlled from the manual automatic switch .9! so arranged that when this switch 695 is in the manual position, it de-energizes relay 406, and when in the automatic position it energizes this relay. Thus, we provide from relay 406,

lead 488 to 490,- to a switch 49L lead 492, 493 to lead 485, transformer 482, lead 484, lead 481' to relay 496. It will thus be seen, if the manual automatic switch 99! is opened, 406 is de-energized and a control of the dies through the manual switch 655 may be accomplished. However, if the operator closes switch 49L the coil 405 is energized, and. this will open the circuit from switch 695 to relay 19. Hence, even if the operator might manipulate the hand switch, no energy would be supplied to coil I9.

It is apparent that, within the scope of the invention, modifications and difierent arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What we claim is:

1. A method of hot chamber pressure die casting employing pressures in excess of one thousand pounds per square inch comprising closing the dies to form a mold cavity, injecting a portion Of the metal at a relatively low pressure on the molten metal and after the cavity has been partially filled completing the filling by injection at a pressure in excess of one thousand pounds per square inch.

2. A method of hot chamber pressure die casting employing pressures in excess of one thousand pounds per square inch, comprising closing the dies to form a mold cavity; injecting a portion of the metal at a relatively low pressure on the molten metal; completing the filling after the cavity has been partially filled by injecting the metal at a pressure in excess of one thousand pounds per square inch; holding the pressure on the metal in the mold until the same becomes set; withdrawing the pressure from the metal in the 24 mold and allowing the metal to cool before the dies are opened.

BURTON F. HOLMES. HERBERT H. HEINDEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,514,103 Rogers Nov. 4, 1924 2,094,080 Parker 1 Sept. 28, 1937 2,098,310 Rockwood Nov. 9, 1937 2,113,033 Poole et al Apr. 5, 1938 2,145,956 Stern Feb; 7, 1939 2,147,449 Lee Feb. 14, 1939 2,173,377 Schultz et a1 Sept. 19, 1939 2,182,059 Schwartz Dec. 5, 1939 2, 07,055 Goodling July 9, 1940 2,277,579 Burger Mar. 24, 1942 2,299,501 Schneider Oct. 20, 1942 2,339,750 Bartholy Jan. 25, 1944 2,363,759 Waldie Nov. 28, 1944 2,494,071 Veale Jan. 10, 1950 FOREIGN PATENTS Number Country Date 594,680 Great Britain Apr. 28, 1939 OTHER REFERENCES General Electric Review, vol. 32, No. 4, April 1929, pages 213 to 223, inclusive.

General Electric Review, vol. 32, No. 7, July 1929, pages 390 to 399, inclusive.

Review of Scientific Instruments, vol. 10, Nov. 1939, pages 323 and 324. 

